Electric meter



(No Model.) 7 Sheets-Sheet 2 T. DUNCAN.

ELECTRIC METER.

No. 605,862. Patented June 21,1898.

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(No Model,) 7 Sheets-Sheet 3.

T. DUNCAN.

ELECTRIC METER.

No. 605,862. PatentedJune 21,1898.

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(No Model.) 7 Sheets-Sheet 4.

v T. DUNCAN.

ELECTRIC METER.

Patented June 21,1898.

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T. DUNCAN.

ELECTRIC METER.

No. 605,862. I Patented June 21, 1898.

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T. DUNCAN.

ELEGTRIG METER.

No. 605,862. Patented June 21,1898.

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' ATENT @rrrcn THOMAS DUNCAN, ()F FORT \VAYNE, INDIANA.

ELECTRBC METER.

SPECIFICATION forming part of Letters Patent No. 605,862, dated June 21, 1898.

Application filedMay 20,1897. Serial No. 637,318. (No model.)

To all whom it may concern.-

Be it known that I, THOMAS DUNCAN, of Fort WVayne, in the county of Allen and State of Indiana, have invented certain new and useful Improvements in Electric Meters, of which the following is a specification.

This invention relates to alternating-cur- I rent meters of that class in which a closed secondary or armature is set in motion by the inductive action of two magnetic fields of differing phase, and in most of its features it relates more particularly to that type of such meters known as integrating wattmeters and in which the two fields referred to are set up, one by coils connected in series in the work-circuit and the other by coils in shunt between the main leads thereof, and in which the movement of the armature is resisted by a magnetic drag. In some of its features, however, the present improvement is applicable to meters of other types.

Among the objects of the invention is to provide a superior instrument of the character referred to and one capable of accurate operation in three-wire systems of distribution as well as in ordinary two-wire circuits.

The invention shows a further development of the principles more fully explained in my concurrent application, Serial No. 637,318, filed August 6, 1897; and it consists in the matters herein set forth, and more particularly pointed out in the appended claims.

In the accompanying drawings, Figure 1 is a front elevation of a meter constructed in accordance with my invention. Fig. 2 is a front sectional elevation thereof, taken on a plane through the axis of rotation of the armature. Fig. 8 is a side elevation of the instrument. Fig. 4c is a top plan section thereof. Fig. 5 is a somewhat diagrammatic view showing the manner of connecting the coils in circuit. Fig. 6 shows a modification in which the shunt-coils are placed at right angles to the position occupied in Fig. 5. Figs? and 8 show two methods of connecting the meter in a three-wire system. Fig.9 shows one method of supplying a supplementary torque to overcome the friction of the parts. Fig. 10 shows a different method of accomplishing the same result.

In said drawings, A designates the meterframe, B the rotary armature, made of cylindric form, and C C and D D the series and shunt coils, respectively. The series coils C O are provided with laminated cores C, of an angular horseshoe shape, made wide at the back, with converging poles arranged on opposite sides of and partially embracing the armature B. Said coils C may either be wound directly upon the cores, as shown in Fig. 5, ormaybe wound separatelyand placed over the ends of the cores, as shown in Fig.

9, and they are made of heavy wire to read-' ily carry the full current of the. circuit in which the meter is placed. As herein shown, the actual connections with such circuit are made by means of binding-posts c, secured to an insulating-block a in the upper part of the meter-frame. The terminals of the coils G are connected with said binding-posts by screws 0, and the circuit-wires are led into the meter-frame through insulating-bushin gs a and secured by the binding-p0st screws 0 The work-circuit is completed through the meter by upper binding-posts 0 to which the circuit-wires are led in through other bushings a, and which binding-posts c are electrically connected by an intervening bar 0 The fine-wire coils D D are provided within the cylindric armature B upon a laminated core D and are connected in shunt between the main leads of the work-circuit. The shuntcircuit is, furthermore, provided with an inductive resistance R, consisting of fine-wire coils wound upon a laminated core R and lo- 'cated in a pocket at the rear of the meterframe. A protecting-casing a incloses the resistance-coils and secures them against injury. The objectof the inductive resistance thus introduced in the shunt-circuit is to ef feet the difference in phase between the current in the volt and series coils necessary to produce the resultant shifting field, by the inductive action of which the armature is set in motion. Such variation in phase should be ninety degrees as near as practicable; but the precise means of producing it, Whether by induction-coils, as described, or otherwise, has nothing to do with the present improvements.

'As hereinbefore stated, the armature B is of cylindric form and is made longenough to extend not only between the cores of the series and volt coils, but also between the poles 2 ceases of two permanent magnets E E, which afford the Foucault or magnetic drag commonly empioyed in instruments of this type. In electric meters as usually constructed the motorarmature is a separate piece from that upon which the drag-magnets operate, and the av pense of manufacture is materially reduced by combining the two in one in the manner stated. Aturther and important advantage of this arrangement arises from the fact that when working under heavy loads the armature sometimes becomes heated, and thereby ol'lers an increased resistance, tending to reduce the torque. With the present construction any heat so developed is rapidly transmitted to the lower part of the armature, and the decreased actuatingtorque due to heating is then neutralized by the decreased drag due to the same cause, so that the tendency to error is compensated for.

As herein shown, both the permanent magnets and the series coils are maintained in position by vertical standards A, rising from the base of the meter-frame. Said standards pass through apertures c in the cores 0 and are provided at their upper ends with nuts a, by which the lamime of the core are clamped down against washers a, that rest on the shoulders provided by the upper ends of the enlarged lower portions of the standards. By making the apertures c of elongated shape the cores may be adjusted toward or from the armature, as desired, to vary the torque in calibrating. The magnets E are herein shown as made of the same shape as the cores G, with wide backs and imvardlyconverging extremities or poles c, which embrace between them a considerable section of the cylindric armature. By this construction the tendency of the lines of magnetic force to leak from one pole to the other without passing through the armature is largely counteracted. The standards A do not in this instan ee pass through apertures in the magnets E, but instead are located at the right dis tance apart to engage the inner angles thereof and so hold them in position, suitable washers and nuts a and a being placed on the standards to clamp the magnets seeurel y down upon the bosses a of the base.

The armature B is herein shown as supported from its upper end by being formed with a top wall I), provided with a huh I), which is secured to a set-screw Z1 upon a spindle l3. The lower end of said spindle rests upon a jeweled bearing Z), provided within a hollow standard D which supports the volt coils and cores by passing centrally through the latter. A spring I)" is placed beneath the bearing o and acts as a cushion to prevent the jewel from being injured by any rough handling of the instrument. The standard D is in this instance screwed into the upper end of a soft-iron core F, that is socured to the base of the meter by a and. projects up into the cylindric armature between the poles of the magnets E, so as to screw j" draw the flux of said magnets through the armature. At its lower end said iron core is reduced in diameter and screw-threzuled to adjustably support a thumb-nut l1", which is made of sullicient diameter to extend beneath the lower edges of the armature, so that it serves to engage and lift said armature it screwed up for that purpose. "When the armature is thus raised by the nut l its hub Z) is brought into contact with the lower end of a stationary centering-tube g and the armature is thus clamped rigidly in place, so that it is not liable to be damaged while being handled or shipped.

The centering-tube r depends from the outer end of the forwardlyn'ojecting arm (l, which is clamped by a thumb-inn; g to a bracket a of the meter-frame. The upper end of the tube g iits within an a 'iertnre in said arm G and is clamped in place by a capnut 9 This cap-nut serves also to support the bearing-tube b, which engages the upper end of the iil'lllilll'll'GSPllHllO, said bearingtube being held adjustably in place within the nut g bya set-screw g. The upper end of the armatuire-spindle is provided with the usual worm b, that actuates the registeringtrain G. The latter is also supported by the detachable arm G, and the sides oi the centering-tube g are cut away, as shown at to permit the engagement of the registeringtrain gear with said worm.

The foregoing construction provides a meter which can be taken apart for examination or repairs with the greatest ol. ease. lly removing the thumb-nut the arm. i and entire upper bearing may be lifted off and the armature withdrawn, and the volt-coils and lower hearing may be then removed by withdrawing the screw f. in this manner the oil-- tire operative mechanism and bearings may be withdrawn by simply disconnecting two screws, and the field-coils and drag-magnet may be as readily released, it desired, by rcmoving the nuts which secure them in position upon the standards A.

Fig. 7 illustrates one method oi placing the meter in athree-wire system oi. distribution, one of the series coils being in this case con nected in one of the outer leads oi. the circuit and the other series coil in the other outer lead and the volt-coil being connected in shunt between said outer leads.

Fig. 8 illustrates a somewhat dillcren t arrangclnent in which the volt-coilsare separm bly connected, one in shuntbetween the other outer lead and the neutral wire. In either case the complete separation of the two series fields by the construction described causes each side of the meter to act, in ellfect, as a dis tinct instrument, so that no matter how the load may vary between the two sides of the system a correct record is always secured. This obviates a very serious l'ault present in meters such as are usually employed. in threewire systems of distribution and resulting from the fact that when one side of the systending to reduce the torque.

tem is loaded heavily and the other only lightly the coil carrying the greater amount of current will force its flux through the Other coil and set up a counter electric-motor force In the case of large meters it is sometimes desirable to provide an auxiliary torque. for the purpose of overcoming the friction of the bearing and registering-train and the inertion of the parts in starting. As shown in f Fig. 9, this is accomplished by providing small fine-wire coils-C upon the field-cores and placing in series with them a non-inductive resistance N. Another and perhaps preferable method of providing such auxiliary torque is shown in Fig. 10, in which the volt coils and core are made capable of an angular adjustment about the axis of the armature. If the core is in line with the field coils and cores, the magnetic flux will be equally divided between the poles of the series coils and no auxiliary torque results. If, however, the volt-core is turned out of line, a larger part of the lines of force will be attracted toward the nearer poles of the series fields and tend to set the armature in rotation. This tendency to rotation, due to the distortion of the magnetic field by the angular position of the volt coils and core, is additional to the rotary tendency due to the shifting resultant field of the series and volt coils when energized by currents differing in phase, and the angular adjustment of the inner core will be such that the two tendencies toward rotation of the armature operate in the same direction.

I claim as my invention- 1. An electric meter provided with a cylindric armature, a shunt-field within the armature, and a series field without the armature comprising separate horseshoe-shaped cores partially embracing the armature, and series coils wound upon said cores.

2. An electric meter provided with a cylindric armature, a shunt-field within the armature, and a series field without the armature comprising separate wide-backed cores having converging poles partially embracing the armature, and series coils wound upon said cores.

3. An electric meter provided with a cylindric armature, shunt and series fields actuating said armature, and a magnetic drag acting directly upon the same armature.

l. An electric meter provided with a cylindric armature, shunt and series'fields actuating said armature, exterior drag magnets acting directly upon the same armature, and an interior magnetic conductor opposite said drag-magnets.

5. An electric meter provided with a cylind ric armature, shunt and series fields actuating said armature, exterior drag-magnets made wide at the back and with converging poles partially embracing said armature, and a magnetic conductor upon the interior of the armature opposite said drag-magnets.

6. An electric meter provided with a cylindric armature closed at its upper end and having a supportin g-spindle revolubly mounted in bearings permitting arising movement of the armature, a nut of larger diameter than the armature and adapted to be screwed up against the lower edge of the armature to lift and close the latter, and a stop between which and the nut the armature may be rigidly clamped.

7. An electric meter provided with a cylindric armature, a series field without the armature, drag-magnets'without the armature, a magnetic conductor within the armature opposite the drag-magnets, a standard carried by said conductor and supporting a magnetic core, and shunt-coils wound upon said core.

8. An electric meter provided with a cylindric armature, a series field without the armature comprising opposite horseshoe-shaped cores and series coils wound upon said cores, a shunt core and coil within the armature and means for adjusting the relative angular positions of the series and shunt cores.

9. An electric meter provided with a rotary armature, a lower bearing therefor carried by.

the meter-frame, and an upper bearing carried by an arm, a lug on the meter-frame against which the inner end of the arm is rigidly seated, and a removable clampingnut holding the arm in place.

10. An electric meter provided with a cylindric armature open at its lower end, a series field without the armature, a shunt coil and core supported upon a standard rising within the armature from its open lower end, a bearing within said standard for the lower end of the armature-spindle, and a detachable arm carrying the bearing for the upper end of the spindle.

11. The combination with the cylindric armature, of the series coils wound upon apertnred cores, standards upon which the cores are bolted, drag-magnets also secured to said standards, a magnetic conductor rising within the armature opposite the drag-magnets,

a standard'mounted upon said conductor and supporting the shunt coil and core within the armature, a lower spindle bearing within the standard, and a detachable arm carrying the upper spindle-bearing.

In testimony that I claim the foregoing as my invention I affix my signature, in presence of two subscribing witnesses, this 18th day of May, A. D. 1897.

' THOMAS DUNCAN.

Witnesses:

CHARLES C. MILLER, H. J. MILLER. 

